Organopolysiloxane compositions which have a long shelf life in the absence of moisture, but crosslink in the presence of moisture are described in U.S. Pat. No. 4,942,211 to Sommer et al., in which the compositions contain alpha, omega-dihydroxypolyorganosiloxanes, silanes containing alkoxy groups and SiC bonded substituted radicals containing substituents selected from amino, mercapto, acryloxy, methacryloxy, epoxy, alkyl, cyclohexyl groups, halogen atoms and cyano groups, condensation catalyst and a salt of a metal of the main and sub groups 2 of the Periodic Table with branched-chain carboxylic acids having from 5 to 15 carbon atoms.
U.S. Pat. No. 3,065,194 to Nitzsche et al., discloses a composition containing a water free mixture of essentially anhydrous hydroxyl-terminated organopolysiloxanes, an essentially anhydrous crosslinking agent of the formula ##EQU1## in which R is a monovalent hydrocarbon radical, Z is an alkoxy or hydroxyl radical, m has an average value of from 0 to less than 2, x has an average value exceeding 2 and m+x has an average value greater than 2 and not exceeding 4, and a metallic salt of a monocarboxyic acid, such as aluminum acetyl acetonate as a catalyst. When the composition is exposed to atmospheric moisture, curing begins almost immediately.
An alkoxy functional silicone rubber composition is described in U.S. Pat. No. 4,100,129 to Beers, in which the composition contains a silanol-terminated diorganopolysiloxane base polymer, an alkoxy functional silane crosslinking agent and a titanium chelate catalyst.
A room temperature vulcanizable composition is described in U.S. Pat. No. 3,127,363 to Nitzsche et al., comprising hydroxyl terminated organopolysiloxanes, organosilicon crosslinking agents having more than two functional groups and condensation catalysts. Examples of condensation catalysts are metal soaps, metal chelates, metal salts of thiols or dithiocarbamic acids, metal oxides and organo metal compounds. The resultant compositions cure at room temperature in from 2 to 24 hours.
U.S. Pat. No. 3,070,555 to Bruner, Jr. discloses organopolysiloxane compositions containing hydroxylated organopolysiloxanes, a siloxane containing silicon-bonded hydrogen and a stannous salt of a monocarboxylic acid. When the catalyst and hydroxylated organopolysiloxane are mixed together, curing of the compositions begins in a very short time and is generally complete within 5 to 20 minutes.
In contrast to the vulcanizable compositions described above, applicant's composition is stable for long periods of time even when exposed to atmospheric moisture. Thus, applicant's composition has a long pot-life, but when heated to an elevated temperature cures rapidly to a solid. Since applicant's composition has a long pot-life, it can be employed on assembly lines where it is used over a long period of time. In addition, the components can be combined together into a single package, whereas, in the conventional compositions it was necessary to keep the compositions away from moisture or to keep the crosslinking agent or catalyst away from the base polymer until ready for use.
Therefore, it is an object of the present invention to provide a composition which is stable in the presence of moisture. Another object of the present invention is to provide a composition which has a long pot-life. Still another object of the present invention is to provide a composition which is stable in the presence of atmospheric moisture, but when heated to an elevated temperature cures to an elastomeric solid. A further object of the present invention is to provide a composition in which the components are combined in a single package. Still a further object of the present invention is to provide a composition which can be crosslinked to form elastomers without releasing corrosive, strongly acidic or basic or noxious-smelling substances. A still further object of this invention is to provide an organopolysiloxane composition which will cure at an elevated temperature to form an elastomer having desirable physical properties.